If you are looking for a tankless unit that can handle large heavy duty applications, look no further. The 1321 series can provide hot water to meet the demands of hotels, resorts and housing complexes. A single unit can produce over 13 gallons per minute. With a single system controller, you can connect up to 24 units, which is equivalent to 316 gallons per minute at 9.1 million Btuhs! With its stainless steel casing and ASME accreditation, no other tankless water heater on the market can match its durability and performance.